Tracking Malaria With Cell Phones

Harvard researchers found they could track the spread of malaria in Kenya using phone calls and text messages from 15 million mobile phones.

"Before mobile phones, we had proxies for human travel, like road networks, census data and small-scale GPS studies," said study author Caroline Buckee, an assistant professor of epidemiology at the Harvard School of Public Health. "But now that mobile phones have spread throughout the world, we can start using these massive amounts of data to quantify human movements on a larger scale and couple this data with knowledge of infection risk."

Buckee and colleagues used mobile phone records from June 2008 and June 2009 to track the timing and origin of calls and texts among 15 million Kenyan mobile phone subscribers. They then compared the volume of subscribers in a particular region to that region's known malaria prevalence. By studying networks of human and parasite movement, the team could then determine primary sources of malaria and who was most likely to become infected.

The results, published Thursday in the journal Science, suggest that malaria transmission within Kenya is dominated by travel from Lake Victoria on the country's western edge to the more central capital city of Nairobi. And human carriers of the malaria parasite, who may not show symptoms, far outpace the flying limits of mosquitoes in endemic regions.

"How travelers acquire malaria elsewhere and bring it home has been mostly surmised from expert knowledge and judgment," said Dr. William Schaffner, professor and chairman of the department of preventive medicine at Vanderbilt University. "Here we've used this unrelated cell phone technology."

With 89 percent of the estimated 1 million annual malaria deaths occurring in Africa, the Harvard findings may help researchers better understand how human travel patterns can spread disease and potentially lead to improved public health efforts to curb the mosquito-borne infection.

"I think it is so neat and extraordinarily imaginative," said Schaffner. "It has me bouncing up and down in my chair with excitement."

Buckee anticipates that mobile technology could change approaches to malaria control. Long-employed anti-malaria strategies, such as the use of insecticides, bed nets, medications and mosquito-habitat removal, could be augmented by warning texts sent to travelers en route to and from malaria hot spots.

"I suspect that some people will get antsy about big brother following you," Schaffner said, alluding to the privacy concerns that accompany mobile technology. "I'm more excited about the possibilities to prevent serious disease."

Buckee said efforts to eradicate malaria in sub-Saharan countries, including Kenya, has been challenged by tight budgets.

"They can't screen and treat everyone," she said. "[Mobile phones] could be really powerful tools for targeting resources with very practical applications."